Slow light propagation throughout photonic crystal slab waveguides have great potential to reduce the size and power consumption of active silicon photonic devices. A great effort has been done to understand the slow light mechanisms and their relations with the waveguide geometrical parameters. In this way, it is expected to control the waveguide dispersion characteristics and exploit the effects produced when slowing down light propagation speed, but avoiding, at the same time, the high group velocity dispersion (GVD) level drawbacks such as pulse broadening and distortion. Here, we present a concise methodology to perform an efficient near-zero GVD slow light photonic crystal waveguide oriented-design. We use a slow light flatness parameter for enabling a systematic comparison of slow light waveguide structures regarding their average group velocity and group index slope within a limited bandwidth. The results show the feasibility of obtain near-zero GVD slow light photonic crystal waveguide structures with slowdown factors up to 40, normalized delay-bandwidth products over 0.2, and dispersion lengths at the millimeter scale.